Comparative Toxicological Effects of Tire Wear and Latex Particle Leachates in Zebrafish Embryos: Focus on Oxidative Stress and Ferroptosis

Microrubber, a subset of microplastics, has emerged as a significant environmental concern due to its persistence, bioaccumulation, and potential toxicity in aquatic ecosystems. This study investigates the toxicological effects of leachates derived from tire wear particles (TWP) and latex particles (LAP) on zebrafish embryos, focusing on physiological, oxidative stress, and transcriptomic responses. LAP leachate exhibited significantly higher toxicity than TWP, characterized by increased mortality, delayed hatching, reduced spontaneous movement, suppressed heart rate, and severe morphological malformations. Chemical analysis identified elevated levels of heavy metals and biologically active organic compounds, with higher zinc concentrations and benzothiazole derivatives in LAP leachate contributing to its greater toxicity. Oxidative stress markers revealed elevated catalase (CAT) and malondialdehyde (MDA) levels in both groups, but LAP exposure significantly reduced glutathione S-transferase (GST) activity, indicating compromised detoxification capacity. Transcriptomic analysis identified ferroptosis as a central pathway mediating toxicity in both leachates. LAP exposure was associated with the upregulation of mt2 and fthl31 and the downregulation of slc40a1, suggesting disrupted iron metabolism and exacerbated oxidative damage. In contrast, TWP exposure triggered adaptive responses, including the upregulation of detoxification-related genes such as cyp1a and gstt1b. These findings elucidate distinct toxicity mechanisms between TWP and LAP leachates and underscore the need for enhanced environmental monitoring and regulatory strategies to mitigate their ecological impacts.